1. Technical Field
The present invention relates to an analytical strip, and more particularly, to the analytical strip for quantitative assays of biological fluids.
2. Description of Related Art
Traditional quantitatively analytical assays utilize a unique capability possessed by the immunological molecules, which they can recognize as well as bind the biological molecules specifically. For example, the traditional enzyme linked immunosorbent assay (ELISA), which is typically conducted in a 96-well plate, characterizes in that determining concentration of an analyte (i.e., antigen) by the intensity of a detected signal resulted from the reaction between the analyte, the corresponding immunological molecules, the enzymes and the corresponding reagents. However, users usually need to perform a tedious washing step at every stage in the assay to wash away the non-binding and the non-specific binding molecules to prevent the assay from failure or in case that the false-positive results occur.
With the progress of technology, nowadays immunological analytical assays are carried out with the analytical strips which have microfluidic channels to simplify, or even omit, the complicated and repeated washing works traditionally required after every reaction stage of the assay. However, the known analytical strip, which is necessary to manually add reagents or substrates required for reactions into the analytical strip, causes inconvenience for the users. The reagents or substrates required for the conventional strips tend to degrade at room temperature or under light after long-term storage, which results in the errors of the assay. Accordingly, such reagents need to be stored in a specific condition, such as cooling or light-proof. Consequently, the conventional analytical strips are nevertheless inconvenient in use and storage.
In addition, conventional analytical strips with channels or micro-fluidic channels have other problems. While such a channel or micro-fluidic channel is typically bordered by a non-absorbent material, and the viscosity of the fluid sample to be analyzed is usually high for the sample is mainly composed of proteins or carbohydrates, part of the fluid sample tends to adhere to the surface of the channel and will not be reacted. Such scenario, if happens, will not only disadvantageously cause the waste of the fluid sample to be analyzed, but also will adversely affects the accuracy of quantifying assays.
In addition, the conventional analytical strip may facilitate the flow of the fluid sample by micro-fluidic channels so that the fluid sample will be delivered via the capillary force exerted by the structures of such channels to the reaction area. Another alternative approach to deliver the fluid sample involves applying a driving force, such as by a pressurizing means, at the time the fluid sample is introduced into the channel so that the fluid sample is propelled to the reaction area through the channel. However, either one of the aforementioned approaches tends to cause air bubbles occurring after the fluid sample is introduced into the channel. These bubbles, either large or small, will block the channel and result in inaccurate analyzing results.